<html>
<script>

var imageLoadResult = 'N/A';
var iframeLoadResult = 'N/A';

function imageLoaded() {
  var image = document.getElementById('denylist_image');
  // Additional sanity check to make sure the image is indeed loaded.
  // Not strictly needed.
  if (image.height == 1 && image.width == 1) {
    imageLoadResult = "success";
  } else {
    imageLoadResult = "error";
  }
}

function imageError() {
  imageLoadResult = "error";
}

function iframeLoaded() {
  // Unfortunately, iframe load errors generally don't result in onerror
  // actually being called, so also check that the title is accessible.
  // Since this is a same-site iframe, it generally should be, unless there's
  // an error page showing in the iframe, in which case it's treated as a
  // cross-domain iframe.
  try {
    document.getElementById('denylist_iframe').contentDocument.title;
    iframeLoadResult = "success";
  } catch (err) {
    iframeLoadResult = "error";
  }
}

function iframeError() {
  iframeLoadResult = "error";
}

</script>
<img id="denylist_image" src="pixel.png" onload="imageLoaded()" onerror="imageError()"></img>
<iframe id="denylist_iframe" src="blank.html" onload="iframeLoaded()" onerror="iframeError()"></iframe>
</html>
